Molecular compounds are molecular assemblies that two or more compounds are bound through relatively weak interactions, other than covalent bonds, represented by hydrogen bonds or van der Waals forces. Molecular compounds containing polymers as constituent compounds are expected to have polymer effects in addition to molecular alignment controls due to intermolecular interactions. Because of this, the molecular compounds have attracted attentions ill recent years as a technique for constructing composite materials called composites, polymer alloys or hybrids. Higher functions given when forming composite are closely related to molecular alignment controls of polymers in polymer assemblies. For example, biomolecules are often involved in expressing functions by becoming composite with or assembling with other molecules, rather than functioning alone. Another example is that, as seen in nucleic acids, a assembly itself plays important roles in expressing higher functions in many cases. As described above, phenomena of polymer assemblies not only are mere interests as materials but also are expected as fields with potentials beyond our present common knowledge, such as retaining and transferring information and formation of specific sites.
Polymer assemblies are formed based on weak, secondary, non-covalent bonding forces working between chains or in a chain, such as Coulomb forces, hydrogen bonding forces, hydrophobic bonding forces, charge transfer bonding forces and van der Waals forces. In particular, assemblies based on hydrogen bonds, which are direction-specific interactions, are expected to be a promising technique to promote highly functional materials by means of forming composites, thanks to the relationship between molecular alignment controls and functions, which has attracted attention in recent years.
A concrete example of polymer assemblies is a complex between polymers. For example, a polymer assembly of polymethacrylic acid and poly(N-vinylpyrolidone) via cooperative hydrogen bonds is known to have very interesting physico-chemical and dynamic properties that are completely different from those of constituent polymers [Makromol. Chem., Rapid Commun., Vol. 1. Page 591 (1980)]. A assembly of polymethacrylic acid mid polyethylene glycol, formed via a similar interaction, has been reported to be a mechanochemical system having a deforming function responding to the environment, which is not found in the constituent polymers [Makromol. Chem., Vol. 176. Page 2761 (1975)].
Such assemblies based on complexes between polymers exist in various forms ranging from very regular shapes such as polymer crystals, polymer liquid crystals or regular higher-order structures composed of assembled subunits found in certain types of biomolecules, to irregular ones found in phase separation phenomena, such as precipitate, gel, coacervate and emulsion.
An effect of a molecular compound containing polymers as constituent compounds comes from the large molecular weights and multi-functionality of polymers: Interactions, separations and cooperative actions, based on functional groups arranged freely in space, are exemplified as polymer effects. However, it is difficult to fix interaction points and to control interaction forces among polymers of which many functional groups exist densely on a single, flexible chain. Therefore it is not satisfactory with respect to stably producing molecular compounds with fixed compositions and structures.
A complex between a low molecule mid a polymer, utilizing interactions with the low molecule is known as a method for controlling the chain structure of the constituent polymer. This method using low molecules, which are easily designed and handled, can easily create a large variety of structures relating to expressing functions, and has attracted attention as a method for aligning and modifying a polymer, in such a way that the constituent polymer is crystallized, made to have a higher melting point or made insoluble due to pseudo crosslinking. Almost no compositions are brown to be widely used in general mid be good for practical use in terms of industrial and basic materials. Only a few examples have been disclosed, including, as those based on van der Waals forces, complexes containing polyethylene oxide mid urea as constituent compounds [J. Polym. Sci., B. Vol. 2. Page 363 (1964)], those containing polyethylene and urea as constituent compounds [J. Macromol. Sci. Phys., Vol. 8. Page 277 (1973)], those containing syndiotactic polystyrene and benzene, and an aromatic hydrocarbon such as toluene or iodine or carbon tetrachloride, as constituent compounds [Polymer, Vol. 34, No. 23. Page 4841 (1993)], and crystalline molecular compounds containing polyethylene oxide and p-dihalogenobenzenes as constituent compounds [Polymer Communications, Vol. 32, No. 15, Page 477 (1991)]; and, as those based on hydrogen bonds, those containing polyethylene imine and water as constituent compounds [Macromolecule. Vol. 14. Page 315 (1981)], those containing polyethylene oxide and hydroquinone, resorucinol or p-nitrophenol as constituent compounds [Macromol. Symp., Vol. 114. Page 51 (1997)] and crystalline molecular compounds containing poly(N-vinylpyrolidone) and 3,5-dihydroxybenzoic acid [Supramolecular Science. Vol. 2, Page 41 (1995)].
In Japanese Laid-Open Patent Application No. Hei 7-331002 (Yamagishi et al.), a resin composition is disclosed which is obtained by adding pentaerythritol to a styrene resin having a carboxylic group. However, this document relates to the improvement of stiffness and fluidity of the styrene resin as a thermoplastic molding material, and does not relate to a molecular compound which is highly aligned by hydrogen bonds as in the present invention.
In Japanese Laid-Open Patent Application No. Hei 2-34813 (Asahina), a resin composition used for sealing a semiconductor is disclosed which includes (a) a denatured epoxy resin, (b) a maleimide resin, (c) a polyphenol resin, and (d) inorganic filler. In this document, the polyphenol resin is used as a hardening agent which reacts with the epoxy resin, and hence, this invention does not relate to a molecular compound which is highly aligned by hydrogen bonds as in the present invention.
In EP 0 397 395 (Kitahara), a resin composition used for sealing a semiconductor is disclosed which includes (a) a polymaleimide compound and (b) phenols as A component and inorganic filler as B component. In this document, also, the phenols are merely added as a hardener.
In U.S. Pat. No. 3,836,590 (Brindell), it is described that a certain polyphenol compound is effective as an antioxidant for organic materials. However, Examples thereof only show polymers having no hydrogen bonding sides, such as polyisoprene or polypropylene, and do not relates to a molecular compound which is highly aligned by hydrogen bonds as in the present invention.
Functions of the polymer assemblies based on the complexes between low molecules and polymers are determined depending on how the low molecules coordinate to the polymers. It becomes therefore very important to control association forms between low molecules and polymers when polymer assemblies are designed and manufactured. It is however difficult to produce polymer assemblies with fixed compositions and structures selectively and stably, because known complexes between low molecules and polymers, based on van der Waals forces are weakly direction-specific in molecular associations. In known complexes between low molecules and polymers, based on hydrogen bonds, constituent polymers applicable with low molecules are very restricted. Besides, functional groups in low molecules, which rule hydrogen bonds, are not arranged properly in terms of directions in the actions. Functions supposed from hydrogen-bonding associations between low molecules and polymers have not been expressed satisfactorily.
In recent years, polymer assemblies based on complexes between low molecules and polymers have attracted attention particularly with respect to functionalities in formulations, waste water treatments, energy transducers, conductors, bio-model reactions and the like. There is only a very little information on roles played by low molecules as well as on solid structures. Compositions that are very satisfactory from the viewpoint of industrially valuable materials have not been found yet.